[Pitchwife]

Alfirin, Quenya and Sindarin aren't so much 'old' and 'modern' forms of the same language as distinct languages, about as different from each other in sound and grammar as, say, Latin and Welsh, although they're both descended from the same ancestor language, Primitive Quendian (just like both Latin and Welsh can be traced back to Proto-Indo-European). But I suppose you can say that Quenya is more 'classical' in so far as it's less changed from PQ than Sindarin is, and also it has at the time of LotR become a language of lore and ceremony rather than a living language - again, think of Latin in medieval and early modern Europe (actually, Tolkien occasionally called it 'Elf-latin', drawing attention to the analogy).